Field of the Invention
The invention relates to a shielded plug connector having a
metal shielding housing with a connection side to which at least one shielded cable is connected and a plug side at which a plug or socket insert having a metal collar is provided such a plug connector is known from German Petty Patent DE-GM 87 13 046.
The plug connector, which acts as a connecting member between self-contained electronic systems and peripherals or the outside, is asked to meet increasingly higher demands for electromagnetic compatibility. The development of electronic systems is characterized by an ever-increasing processing speed, or in other words high clock frequencies, in digital computation and control systems. That sharply increases the sensitivity to high-frequency factors. Those interference factors can lead to malfunctions that have a direct effect on the quality of the systems. On the other hand, interference factors also originate in electronic systems or appliances themselves that operate with steep-edged high-frequency signals in both the control and the power portions. In order to reduce or even completely cancel out the mutual influence of electronic systems on one another, the plug connector, as an interface element between a self-contained electronic system and its surroundings, is of decisive significance. The plug connector known from German Petty Patent DE-GM 87 13 046 is intended for those purposes. It has a two-part housing, and shielding plates or shrouds line the inside of the individual housing parts to provide electrical shielding. When the housing is put together, the shrouds are electrically connected, not directly, but rather by contact being made with the metal plug inserted into the housing and with a shield of a cable guided into the housing. In that plug connector, the metal plug body with its collar is disposed on the outside of the plug connector, on the plug-side end of the lower housing part. The connecting cable is connected mechanically by means of a collar clamp to the lower housing part, and electrically to a shroud disposed in the lower housing part.
In other commercially available plug connectors, the housing is put together from two half-shells, between which slight gaps may be present that considerably influence the shielding action. In the case of such housings, various shielding materials are used, such as solid-cast half-shells of aluminum, metal plates placed in plastic half-shells, or metallized plastic half-shells. Those half-shells are each electrically connected to the shielding braid of the cable and to the metal collar of the built-in plug. The metal collar of the built-in plug is usually fixed, and protrudes from the end surface of the housing. Accordingly, in typical plug pairs having one counterpart plug in the back or front wall assembly and one plug in the housing of the plug connector, there are gaps, specifically gaps between the counterpart plug and the wall and between the plug and the housing. In such plug connectors, there are accordingly a great number of junction points, and the flow course of the interference signals, which are to be diverted to ground, is finally as follows: cable shielding braid--housing wall--metal collar of the plug--metal collar of the counterpart plug appliance wall (ground). Surface currents can be carried into the interior of appliances, and/or interference factors can originate in the appliance itself.